Anhedonia and amotivation are two main negative symptoms of schizophrenia and affect significantly the everyday life functional activities engagement in people with schizophrenia such as goal-directed behaviour and decision-making. Most of the previous work has been limited to behavioural findings and it is still unclear the underlying neural mechanism of motivational anhedonia observed in patients with schizophrenia. Drs. HUANG Jia and CHAN Raymond from the Institute of Psychology have conducted a study specifically to examine whether the observed impaired effort expenditure decision-making in schizophrenia was associated with dysfunction of the nucleus accumbens and the associated forebrain regions.
They scanned the brain activations of 23 patients with schizophrenia and 23 healthy controls while they were undertaking an effort-based task involving different ranges of reward magnitude and probability of getting the rewards. Their findings showed that people with schizophrenia demonstrated dysfunction of the nucleus accumbens, the posterior cingulate gyrus, and the left medial prefrontal gyrus when performing the effort-based decision-making task comparing to the healthy controls. Neural activations were significantly correlated with choosing hard tasks and hedonic processing people with schizophrenia. However, there was no association between reward probability and magnitude observed in people with schizophrenia. On the contrary, healthy controls demonstrated a significant association between reward probability and magnitude while they were performing the effort-based decision-making task. These findings suggest that the nucleus accumbens, the posterior cingulate gyrus and the medial gyrus play an important part in willingness to expend high-level effort to obtain higher consummatory pleasure experience, especially when there is uncertainty to obtain the reward. However, these functions are impaired in people with schizophrenia leading them to have impaired effort expenditure decision-making.
This study was done by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences, the National Natural Science Foundation of China and the Beijing Training Project for the Leading Talents in Science & Technology, and the Key Laboratory of Mental Health, Institute of Psychology.